Method development and validation for the extraction and quantification of sesquiterpene lactones in Dolomiaea costus

Dolomiaea costus, commonly known as Indian costus, is a medicinal plant from the Asteraceae family. The root and powder of costus have been widely used to treat various health conditions. The primary bioactive compounds in this plant are sesquiterpene lactones, particularly costunolide and dehydrocostus lactone. This study aimed to establish a rapid, environmentally friendly, and cost-effective method for the high-throughput extraction and quantification of sesquiterpene lactones in Indian costus. Ultrasonic bath (UB) and UPLC/MS-MS were employed to extract and analyse 49 Indian costus samples. Aqueous ethanol was identified as the most effective solvent system for extracting and analysing sesquiterpene lactones. The extraction efficiency of the ultrasonic bath was comparable to that of the ultrasonic homogeniser while shaking showed the lowest efficiency. The environmentally friendly UPLC/MS-MS analysis revealed mean concentrations (±SD; μg/100 μg) of 1.00 (±0.39) for costunolide and 0.70 (±0.25) for dehydrocostus lactone. An inverse correlation was observed between sesquiterpene lactone content and sample colour. Most samples contained costunolide levels above the minimum limit (0.6 %) specified by the Chinese monograph, but only a few met the 1.8 % threshold for total sesquiterpene lactones. Given the importance of bioactive sesquiterpene lactones for medicinal efficacy, insufficient levels may result in diminished therapeutic value. Therefore, standardising Indian costus products is crucial to ensure quality and appropriate dosing. This study contributes to the standardisation of Indian costus, a vital step towards ensuring the efficacy and safety of herbal products.